Device for clamping tools



June 19, 1951 F TURRETTlNl 2,557,582

DEVICE FOR CLAMPING TOOLS Filed April 29, 1947 2 sheets-sheet 1 /4l LL 4 i l Fig. I

o /NVENTUH 32 Fernand Emfff/H' E), y 30 MMM June 19, 1951 F. TURRr-:TTxNl DEVICE FOR CLAMPING TooLs 2 Sheets-Sheet 2 Filed April 29, 1947 ATTo/VEY Patented `lune 19, 195i UNITED g STATES DEVICE FOR CLAMPING TOOLSV Fernand Turrettini, Geneva, Switzerland, as-l signor to Societe Genevoise DInstruments de Physique, Geneva, Switzerland, a rm of Switzerland l Application April 29, 1947, Serial No. 744,558

. vIn Switzerland May 3, 1946 9 IClaims. (Cl. Sli-11) The clamping oftools o n rotary machine tool spindles such ras milling and boring machines, is, generally speaking, obtained by a clamping taper, e. g. a Morse taper or the like, permitting accurate centering as well as rigid clamping of the `tool on the spindle.

Various means haveh-eretofore been used in order to clamp and then release the tool.v

Themost commonly used device consists of a clamping bar which extends the whole length of the spindle and screws into the shaft of the tool. This bar must be screwed in and screwed out by hand, generally by gripping its extremity opposite to the tool, a procedure which absorbs a considerable amount of time, especially if the spindle arrangement is such as to compel the op erator to change his position.

In order to reduce to a minimum the idle time of the machine, devices have been proposed Vto permit changing the Atool 4in a minimum of time by applying a simplied tool-holding system op erated either by hand or automatically, as well as a braking device which stops the spindle quickly. Anobject of thepresent invention is to provide a device intended to clamp and release the tools on the rotative spindle of amachine tool, including a draw-in bar provided with a screw `thread arranged concentrically to the spindle and cooperating with a screw thread provided on the tools to be clamped. The device in accordance with the invention is characterized by a transmission mechanism connecting the draw-in bar to the spindle-driving motor so that, when the spindle is thrown out of gear, the motor acts| on the draw-in bar through a coupling and, -according to its direction of rotation, eilects the clamping or the releasing of the' tools.

The accompanying drawings illustrate, by way of example, a preferred embodiment of this device.

In the drawings:

Figs. 1 and 1A are together a longitudinal section of the spindle; 1

Fig. 2 illustrates a cross-section. of a detail of design taken approximately on the line II-II in Fig. 1.

In the Fembodiment illustrated in the drawings, .the spindle I, running in bearings 2, 3, l of the housing 5, is adapted gto receivethe tool 6 at its righiJ handextremity. Thefshaft of the tool is provided with'a-taper portionv 1, intended to fit finto a corresponding conical recess I of `the'spindle and a square portion 8 lttingrin a recess 9 of the spindle. A transmission for driving the spindle at various speeds of rotation is diagrammaticallyrepresented by a single pair of gears I0 and Il mounted respectively onthe spindle I and a drive shaft Ila. A double-acting disc clutch I2vpermits the shaft I Ia to be coupled either with a pulley I3 driven by motor I4 and pulley I4 to produce rotation of the spindle, or with a brake I5 rigidly secured tothe housing 5 for quickly Stopping and immobilizing the spindle to change the tool. 1

Internally of thespindle and coaxial therewith, a draw-in barl I6 is so arranged that it can rotate but cannot slide axially. Its right hand end is provided with a machined portion I1 and a square I8. A stopping ri1' 1g I9, fixed on the spindle by means'not shown, stops axial movementof the bar I6 in both directions, cooperating on one side With the shoulder 20 of the bar and,v on the other side, with the face 2l of a screw-threaded ring 22 mounted on the square I8 and retained by screw 23 and washer 23'. The ring 22 has an external screw thread 24 adapted to screw into a tapped hole provided in the tool shaft for that purpose. f

Atthe opposite end of bar I6, there is a square 25, on which a sliding sleeve 26 is mounted, and a reduced end portion Ilia. A compression spring 21 mounted on the end portion Ia of bar I6 bears at one end against a collar 6B seated on an abutment 6I secured to the end of the portion I6@ and at the opposite end presses against a collar 62 which is slidable on the portion Ilia and bears on thesliding sleeve 26. Thus, spring 21 constantly tends to push the sleeve 26 against shoulder 28 ofthe bar I6.V Sleeve 26 is operated by alever 29, pivoted at 36 and resiliently coupled by means of springs 21 to the armature 3 I of an electromagnet of which the core 32 is fastened onto the housing 5 of the spindle. The electromagnet and the springs 21 and 21 are computed in such a way that when the electro-v magnet is energized the armature slides ysleeve 26 along the square by means of lever 29 overcomingthe -action of spring 21. In this position; sleeve 26 yand ring 33 are coupled together by teeth 34 on sleeve 26 and teeth 34 on ring 33 being in mesh. When the electric current is cut 01T in the electromagnet, its action on the lever ceases and spring 21- againpushes the sleeve vagainst shoulder 28 of the bar, thus releasing the coupling. Ring 33 is centered in a cup-shaped driver 35 and coupled'to thelatter by a friction clutch constituted by a series of springs 36 located in recesses 31 (Fig.,2 of ring 33 and acting'through appropriate friction members on both faces 38 and 39 of driver 35. A wedge 40 (Fig. 2), biased by a spring 4I, is located in a recess 42 provided at the periphery of the ring to prevent its sliding with respect to the driver when the latter rotates in the direction indicated by the arrow. By this arrangement of the clutch, it is possible to transmit to the bar I6, in one direction, a couple limited by the power of the springs 36 for the clamping of the tool, and, in the opposite direction, a maximum couple for its release.

The driver 35, mounted at the end of a shaft 43, is operatively connected to the driving motor of the spindle by means of a planetary speed reducer 44 so that it revolves with Vreduced speed. In the example illustrated, the periphery of this speed reducer is rim-shaped to be driven by means of a belt by pulley 45 rigid with pulley.

I3, the latter being belt-driven by the pulley I4' of spindle motor I4. By its rotation, the body of the speed reducer 44 drives satellite pinions 46 meshing with a iixed gear wheel 4-1. Opposite satellite pinions 48 rotate with the same speed as the pinions 46, on which they are dependent, and are in mesh with the toothed wheel 49, rigid with driver 35. The reduction ratios between the toothed wheels 41, 49 and the satellite piuions 46, 48 are chosen iny such a way as to reduce the speed of driver 35 suiiiciently to prevent a too sudden coupling action which would prove detrimental to the entire mechanism. Y

For clamping a tool 6, a-convenient handle 50 controlling rthe disc coupling clutch I2 and the brake I is operated so -as to release and stop the spindle. The pulleys vI3 and 45, and the speed'reducer -44 continue to rotate as do also the driver 35 and ring 33. These latter components, however, rotate with reduced speed. Now taper 'i of the tool is introduced into the spindle taper `I the rectangle :8 penetrating in the corresponding recess 9 of the lspindle nose. At this precise moment, a push-button l5| is operated to energize the electromagnet and thereby -actuate the lever 29 to slide the sleeve 26 along square 25 into engagement with ring 33. The latter thus 'transmits its 'rotational motion to bar I6. The direction of the screw thread is such that, 4by this rotation, the ring nut 22 penetrates into, the tapped hole provided/in the shaft of the tool, pulling the latter quickly inside for tightening it in the taper I' oi the spindle. As soon as the clamping takes place, the bar as well as the sleeve 26 and the ring 33 Yare immobilized. The above described friction clutch goes vinto action, limiting the couple transmitted 'to the draw-in bar. The Vpush-button 5I is now released -to deenergize the electromagnet, whereupon the spring 21 drives back sleeve 26 and releases rod I6. The ring v'33 lag'ainstarts Vits rotational lmotion, being operated by the driver 35. The -spindle beingnow ready for working, the lever 5U is operated lto engage the clutch and ythereby connect the spindle with the spindle motor I4.

'I'o 'release vthe tool, the spindle is immobilized by operating lever 50 and the loperator 4then pushes la releasing push-button 51" which reverses the direction of rotation of 'the spindle `motor and energizes 'the electromagnet to effect, as previously, the coupling Yof bar I6 with the driver 35. Due to the '.f-actlthat the releasing 'of the tool may require :a relatively substantial effort, itis advisable to exert on .the bar :a maximum couple which is greater than .that provided by the fric- .tion clutch of ring 33. As already mentioned, this -is 4obtained by means voffwedge 40 (Fig. 2)

which compels ring 33 to rotate together with driver 35 in this direction of rotation. The couple transmitted to bar I6 is moreover subject to a proportional increase with respect to the reduction ratio of the speed reducer. The tool having been withdrawn and released by this rotation of the screw-threaded bar, the push-button 5I is now released to release the bar I6, and the spindle motor I4 stops.

In the embodiment of the invention which has been described, the coupling of the draw-in bar I6 with the driving element 33 is obtained by the cooperating action lof an electromagnet and oi an opposing spring. It will be readily understood that any other equivalent means could be applied, such as .hydraulic or pneumatic means with remote control.

What I claim is:

1. vIn a machine tool, the combination comprising a spindle for receiving a tool, means for driving said spindle, first means for 4coupling said spindle to said driving means, a brake for said spindle, means for controlling said coupling and said brake for effecting a disengagement and a stoppage `of said spindle for the purpose of tool changing, a draw-in member disposed rfor rotation within said spindle having a portion formed to engage a tool, means for rotating said member including means for operatively linking said rotating means to driving means, second means for coupling said rotating means to said member, and means for actuating said second coupling means.

2. The combination according to claim i, wherein lsaid vfirst coupling -means includes a clutch mechanism.

3. The combination according lto claim A1, wherein said iirst coupling means includes a clutch and said controlling means comprises a lever mechanism for actuating said clutch and said brake.

V4. The combination according to claim 1, wherein said rotating means includes a speed reducer.

`5. The combina-tion according to claim 1, wherein said second coupling `means includes Ya second clutch.

-6. The `combination according vto claim 55, wherein said second clutch includes automatic stopping means 4limiting the torque from said rotating means to said member in one direction and for transmitting a maximum turningmoment in the other direction.

'7. The combination according to claim l1, wherein vsaid actuating means includes an electromagnetic mechanism.

8. The combination according to claim l, further including 'means for reversing the voperative sense of direction -of said driving means.

l9. The combination according to -claim l, wherein said actuating meansincludes an electromagnetic mechanism further'including a control comprising two push buttons vfor controlling respectively said electromagnetic Vmechanism and the reversing of said driving means.

'FERNAND REFERENCES CITED UNITED STATES PATENTS Name Date Turremni May 4 194s Number 

